摘要本文以T2纯铜为原料，利用新研制的旋转加速喷丸设备进行表面纳米化处理，观察其微观组织和硬度。另外对于处理后样品的热稳定性进行研究，观察不同退火条件下表面纳米化处理纯铜样品的组织及性能变化。得到以下结论：67476

     1．成功对纯铜表面进行处理，在纯铜表面约100m范围内实现了纳米层，最表面硬度为217HV，远高于未处理粗晶纯铜样品的硬度。距离样品表面100~500m为变形影响区，区域内原始大晶粒被拉长，呈现典型压力变形组织结构。

     2．对样品进行DSC测试，结果表明纯铜样品在70℃到150℃之间有一个明显的放热峰，峰谷出现在95℃左右。

     3．对样品进行SEM结构观察和硬度测试，发现样品在不同的退火温度下微观结构与表面硬度均发生明显的变化。

4．处理后纯铜样品在90℃退火时结构较为稳定，继续升温会发生晶粒长大，从而影响纳米化处理效果。因此需要结合其它工艺以提高表面纳米化处理后样品的热稳定性能。

毕业论文关键词  表面纳米化处理  热稳定性  微观结构   硬度

毕业设计说明书（论文）外文摘要

Title    Thermal stability of surface nano-crystallized Cu       

Abstract In this paper, T2 copper was used as raw material, and a newly developed Rotation Accelerated shot peening (RASP) machine was used to introduce nanocrystalline on the surface of the Cu samples. Microstructures and hardness of the RASP treated Cu were observed. In order to study the thermal stability of the as-RASP Cu, the microstructures and the hardness of different RASP Cu under different annealing conditions were also investigated. The following conclusions can be drawn:

1. RASP treatment successfully introduced severe plastic deformation to Cu surface, approximate 100m thick nano-layer was achieved within the most surface, and the surface hardness was 217HV, far higher than the untreated samples of coarse-grained copper hardness (154HV). From the sample surface 100 ~ 500 um for the deformation zone, the original area of large grains are elongated, showing a typical deformation structure.

2. DSC test results showed that the copper samples had an obvious exothermic peak between 70 ℃ to 150 ℃, with the peak temperature about 95 ℃.   

3. By SEM observations and hardness tests, we found that hardness and microstructures changed significantly when suffering from different annealing temperatures.

4. The RASP treated copper samples was kept stable when annealed at 90 ℃ for 10 minutes. Further increase the temperature will lead to grain growth,   which influenced the nano-crystallized effect. Therefore a combination of other processes was required in order to improve the thermal stability of the as-RASP samples.

Keywords    Surface nanocrystallization,  Thermal stability,  Microstructure,  Hardness

目   次

1 绪论 1

1．1 纳米材料的简介 1

1．2 纳米材料的制备 2

1．3 严重塑性变形法制备纳米材料现状 3

1．4 表面纳米化的基本原理、制备方法和技术优势 4

1.4.1 表面纳米化的基本方式 4

1.4.2 塑性变形致金属材料表面纳米化 5

1.4.3 金属材料表面纳米化技术优势 6

1．5 纯铜表面纳米化